Table 1 Condition optimization for the allylation of β-boronyl estersa.

From: A unified approach for divergent synthesis of contiguous stereodiads employing a small boronyl group

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Entry

1

Solvent

Additive

Yield (3 + 4) (%)

d.r. (3/4)

1

1a

THF

none

65

1:2.4

2

1a

Toluene

none

0

–

3

1a

THF/Toluene (1:1)

none

69

1:3.9

4

1a

THF

HMPA

33

> 20:1

5

1b

THF/Toluene (1:1)

none

77

1:10

6

1b

THF/Toluene (1:1.5)

none

77

1:11.8

7

1b

THF

HMPA

50

> 20:1

8

1c

THF/Toluene (1:1)

none

75

1:3.5

9

1c

THF

HMPA

75

> 20:1

  1. aReaction conditions: 1 (0.25 mmol), 2 (1.5 equiv), LDA (1.1 equiv), HMPA (0.2 mL, if used) in 1 mL of solvent at −78 °C for 12 h. Yields and diastereoselectivities were determined by 1H NMR analysis of the crude reaction mixture with 1,3,5-trimethoxybenzene as an internal standard.
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